Group II chaperonins, which assemble as double-ring complexes, assist in the refolding of nascent peptides or denatured proteins in an ATP-dependent manner. The molecular mechanism of group II chaperonin assembly and thermal stability is yet to be elucidated. Here, we selected the group II chaperonins (cpn-alpha and cpn-beta), also called thermosomes, from Acidianus tengchongensis and investigated their assembly and thermal stability. We found that the binding of ATP or its analogs contributed to the successful assembly of thermosomes and enhanced their thermal stabilities. Cpn-beta is more thermally stable than cpn-alpha, while the thermal stability of the hetero thermosome cpn-alphabeta is intermediate. Cryo-electron microscopy reconstructions of cpn-alpha and cpn-beta revealed the interwoven densities of their non-conserved flexible N/C-termini around the equatorial planes. The deletion or swapping of their termini and pH-dependent thermal stability assays revealed the key role of the termini electrostatic interactions in the assembly and thermal stability of the thermosomes.
Flexible interwoven termini determine the thermal stability of thermosomes.,Zhang K, Wang L, Liu Y, Chan KY, Pang X, Schulten K, Dong Z, Sun F Protein Cell. 2013 Jun;4(6):432-44. doi: 10.1007/s13238-013-3026-9. Epub 2013 May, 25. PMID:23709365[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑ Zhang K, Wang L, Liu Y, Chan KY, Pang X, Schulten K, Dong Z, Sun F. Flexible interwoven termini determine the thermal stability of thermosomes. Protein Cell. 2013 Jun;4(6):432-44. doi: 10.1007/s13238-013-3026-9. Epub 2013 May, 25. PMID:23709365 doi:10.1007/s13238-013-3026-9
